momentum fluxes and wind gradients in the marine boundary layer — a multi-platform study
نویسندگان
چکیده
During five autumn weeks, measurements of turbulent fluxes were obtained in the Baltic Sea at three levels on a 30-m tower and two levels on an ASIS buoy 4 km from the tower together with profiles of wind and temperature. Wave data and SST were obtained from ASIS. In the mean, momentum fluxes measured on the tower and on ASIS during onshore winds agree closely. Dimensionless wind gradients fm(z/L) for (i) stable conditions are linear in z/L (L is the Obukhov length); (ii) unstable, growing sea conditions are much smaller than predicted by ‘standard’ equations, due to an indirect effect of the boundary layer height. Individual wind profiles extrapolated from ASIS to tower by integration of fm(z/L) deviate by about 0.5 m s –1 from measured values, but corresponding mean profiles agree well for all levels from 1.18 m to 30 m. This random variation in the wind field is shown to be related to inherent dynamics of the atmospheric surface layer.
منابع مشابه
On momentum flux and velocity spectra over waves
Data from a research tower in Lake Ontario are used to study the validity of MoninObukhov scaling in the marine atmospheric boundary layer under various wave conditions. It is found that over pure wind seas, the velocity spectra and cospectra follow established universal scaling laws. However in the presence of swells outrunning weak winds, velocity spectra and co-spectra no longer satisfy univ...
متن کاملTurbulence Structure of the Hurricane Boundary Layer between the Outer Rainbands
As part of the Coupled Boundary Layers Air–Sea Transfer (CBLAST)-Hurricane program, flights were conducted to directly measure turbulent fluxes and turbulence properties in the high-wind boundary layer of hurricanes between the outer rainbands. For the first time, vertical profiles of normalized momentum fluxes, sensible heat and humidity fluxes, and variances of three-dimensional wind velociti...
متن کاملبررسی پارامترسازی عمق لایه پایدار شبانه و تاثیر آن در آلودگی هوای یک منطقه شهری با توپوگرافی پیچیده (تهران)
Mixing height of the atmospheric boundary depends on the vertical variation of temperature in the atmosphere which includes temperature inversion (including surface and elevated inversions) that has a significant effect on air quality. The mixing height like some other meteorological variables has diurnal variations. The reason for that is its dependence on some other basic meteorological param...
متن کاملThe study of effective stress and pore water pressures in the foundation of a concrete gravity platform affected by loads due to waves, currents and wind in the Persian Gulf
It is proposed to use a single base platform in the Persian Gulf considering its low depth and more appropriate environmental conditions in comparison to North Sea and Mexico Gulf where this kind of platform is very popular. The pile of platform is responsible for transmission of environmental loads resulted from waves, currents, wind and dead loads to foundation of platform. Using SACS 5.3 sof...
متن کاملCoupled Dynamics of the Wave-Atmospheric Boundary Layer at Strong Winds
The main goal of the proposed research is to study theoretically the role of the breaking wind waves and the sea spray, generated by them, under strongly forced situations in the airflow dynamics in particular in energy, momentum, heat and moisture transfers through the sea surface. Through this to increase the knowledge of the air-sea interaction and to apply this knowledge for developing impr...
متن کامل